Storing form data into wordpress database [closed]

This is a simple code to add a form in a page:

add_shortcode( 'myform', 'add_myform' );
function add_myform( $atts ) {
    if ( isset( $_POST['myname'] ) ) {
        $myname  = $_POST['myname'];
        update_option( 'myname', $myname );
    } else {
        $myname = get_option( 'myname' );
    }

    $myform = "<form method='post' action=''>";
    $myform .= "<input type="text" name="myname" value="" . $myname . "">";
    $myform .= "<input type="submit" value="Submit">";
    $myform .= "</form>";
    return $myform;
}

Add the shortcode [myform] in a page and the form will be shown.